Libidn FAQ -- Anticipated Frequently Asked Questions.
Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007 Simon Josefsson
See the end for copying conditions.
Q#1: Why doesn't Libidn use a separate library for the Unicode
operations?
A#1: Separate libraries (Glib, QT, libiconv) seldom mark the
Unicode tables with the corresponding Unicode version they
implement, nor do they provide a interface where a specific
version can be requested. This violates the stringprep
specification which requires that a specific version must be
used. Also, some of these third party libraries depend on
non-portable behavior (e.g. threads).
Q#2: Why do Libidn include several stringprep profiles? They waste
space!
A#2: The stringprep profiles included are usually derived from the
generic stringprep tables, and doesn't waste more than say a few
hundred bytes (see profiles.c). The Unicode normalization tables
and the generic stringprep tables are roughly equivalent in size,
although the latter tables can surely be compressed much further.
They occupy about 100 kilobytes on typical platforms. However,
if in the future several large Stringprep profiles are added,
configure options will be added to help reduce size.
Q#3: I thought GNU was encouraging libraries to be licensed under the GPL?
A#3: The reasoning for this was for libraries that provide unique
functionality to encourage more free programs. Since there are
several IDN libraries out there, using the GPL for Libidn would
only encourage people not to use Libidn which would not help the
spread of free software.
Q#4: How do I add a new stringprep profile?
A#4: Add the profile definition to profiles.c, export the symbol and
optionally add a CPP macro in stringprep.h.in (and document it in
stringprep.c). If you want to add self tests, do it through
tst_stringprep.c. Mention it in NEWS.
----------------------------------------------------------------------
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.